You can see the up/down arrows in the screenshots, which indicates that he was not only logged in (because of the existence of the down arrow), but hadn't yet voted.
No point in contaminating his 'evidence'.
Really, you're reading a lot in to very little.
Argue the case of the downvotes, not the man behind the criticism, of course he could have upvoted them, but he still can, can't he ?
In other words, it's not worth complaining about downvotes until good comments are getting stuck in negative territory and you can't do anything about it. When that happens, I think that this is a discussion worth having. I don't think we're there yet.
Argue the case of the downvotes
I did, in my 2nd and 3rd paragraphs (the majority of what I wrote).